Snakes on a Planerepresents the ideal of contemporary major-studio filmmaking -- which is to say, major-studio marketing. Who needs word-of-mouth screenings or critics when you can sell the four-word pitch as written on a napkin? It points to a future that takes all the guesswork out of moviegoing. A major-studio release will be simply a referendum on the titular concept, and the audience will vote by casting its box office ballot for Big Ol' Boobs or Shoot Gun Now or As Seen on PlayStation! Only one question will need to be answered: Does the movie deliver what it promises?

The answer, in this case, is yes, holy Jesus, yes: There are snakes up in that motherfuckin' plane, yo -- fat snakes, skinny snakes, snakes with Groucho eyebrows and sporty little curled fangs. It's the Ben-Hur of herpetology. And with a passenger list of succulent nobodies serving as in-flight snacks, Snakes on a Plane goes about its give-the-people-what-they-want mission with a crassness so single-minded it's positively gleeful. There's something almost refreshingly venal about a movie with no purpose other than to meet intentions this cheesy. But a viewer can feel he's gotten exactly what he paid to see from this dream in-flight movie and still leave wondering, "Is that all I wanted?"

Snakes on a Plane wears its B-movie shamelessness -- its most winning feature and salable commodity -- like the swanky pheromones the baddies use to goose their crate-load of venomous serpents into a feeding frenzy. From a dozen straight-to-video thrillers, it swipes the old setup with the dogged FBI agent (Samuel L. Jackson, by this point practically a high concept in himself) transporting a witness in protective custody. From Irwin Allen's TV-movie knockoffs of his money-minting disaster-movie formula (Fire! Flood! Cave-In!), it borrows the combination of a Grand Hotel character assortment and a Budget Inn cast, stocking the coach section with types such as the Attendant Who Sure Hopes Her Last Flight Is Quiet (Julianna Margulies, in the Karen Black Airport 1975 role), the Pissy Guy You Can't Wait to See Constricted, and Woman with Plump, Juicy Baby.

A filmmaker with a sense of embarrassment might try to play down the obviousness of these stock characters and their Fisher-Price exposition. Not so director David R. Ellis, a veteran second-unit man who showed mad genre-movie skillz with Final Destination 2 and Cellular. Ellis emphasizes their phoniness to the point of absurdity, draping the travelers in ridiculous leis and turning them into a frequent flyer's worst nightmare of sneezy, wheezy, sleazy humanity. (As in the recent Red Eye and Flightplan, mass transit is a Sartrean hell of other people.) When the snakes finally show up -- part of a showboating Asian-American gangster's uniquely far-fetched assassination plot -- they run amok among these stereotypes like the film-shredding gargoyles in Joe Dante's Gremlins sequel. All but winking at the camera, they gouge eyes, barge in on the Mile High Club and give zipper-clenching new meaning to the term "trouser snake."

And yet for a movie that trades explicitly on its audience's phobias of snakes and tight spaces, Snakes on a Plane does surprisingly little with either fear. The en-masse snake attacks are staged with splattery verve and sick humor: If Mad TV had the balls-out tastelessness to parody United 93, it might resemble the montage of passengers taking up arms against their slithery foes. But the many wriggling CG snakes look silly instead of scary. The ornery 3-D solidity of one real rattler is worth two dozen pixelated pythons, and there are so many of the damned things that none develops any real presence or villainy. (You wait for Jackson's tough guy to reveal an Indiana Jones-style weakness for reptiles, but alas, he remains dully superhuman.) The set, moreover, is one of those multilevel enormo-jets with the plush upstairs lounge -- a setting, in the no-frills Southwest era, as far removed from most people's experience of flying as zeppelin travel. It's rarely confining enough to bring out the creepy-crawly effectiveness of the premise: the threat of reaching into an overhead compartment and finding snakeskin that isn't a jacket.

Seen with a big unruly audience laughing in disbelief at its own willingness to get on board, the movie is a lot of fun -- a communal midnight-movie experience in prime time. In the end, though, Snakes on a Plane seems destined to be better remembered as a Web phenomenon -- a Trivial Pursuit question circa 2015 -- than as a movie. Ellis has undeniable flair as a craftsman of big chaotic set pieces, and he creates a distinctive tone that's close to poker-faced parody: Let it not be said that he hasn't delivered exactly the movie promised by the title. But people used to go to genre movies to get what they didn't expect -- the you-know-you-want-it teasing of Brian De Palma's voluptuous psycho thrillers, or the unsettling ambiguity of Paul Verhoeven's corrosive hard candy. Snakes on a Plane, for better or worse, is essentially a movie on demand. Like the flailing airline industry -- which probably sent executives out for ice packs when they heard the title -- it gives you the ride you paid for, and nothing extra.